Rain, sleet, and snow have always presented a vision problem for the operator of a vehicle. While mechanical movement of a wiper blade across a windshield is partly effective as a mechanical squeegee to displace water and snow from a windshield. The operation of a conventional wiper blade, regardless of whether made of carbon-base or silicone rubbers, is only partially effective in clearing water and snow from a windshield. A wiper blade moving across a windshield leaves a thin film of water that partly impairs vision and promotes adhesion of additional liquid water or snow to the windshield. Additionally, as a wiper blade undergoes degradation through exposure to the environment, the uniformity of wiper blade contact with the windshield is degraded. Additionally, debris that commonly adheres to the windshield creates regions in which wiper blade is gapped from the windshield surface leading to vision obscuring streaks and water droplets.
To address limitations of windshield cleaning through mechanical squeegee action, hydrophobic glass treatment solutions have been applied to automotive windshields to improve driver vision under high humidity conditions of rain, sleet, or snow. Representative of such glass treatments are those detailed in U.S. Pat. Nos. 3,579,540, 5,688,864, 6,432,181. While such glass treatments are effective in rendering the windshield hydrophobic so as to cause water to bead and not form windshield water film, these products have met with limited acceptance owing to the labor-intensive application, and somewhat toxic chemicals needed to be handled to create a hydrophobic windshield surface. Additionally, the application of such hydrophobic glass treatments while a windshield is being subjected to rain or other precipitation is impractical.
In recognition of the limitations of conventional hydrophobic glass treatments, coating compositions have been developed for a wiper blade that include a silicone wax, a silicone oil in a solid lubricant such that the wax dissolves in the silicone oil such that during operation of the wiper blade, components of the coating layer are transferred onto a contacting windshield through the friction of the wiper blade against the windshield. Such a composition is detailed in U.S. 2010/0234489. While such a coated wiper blade is effective in delivering a hydrophobic coating to a windshield upon wiper blade installation, the ability of the coating to be transferred to the windshield is rapidly degraded to the point where the ability to transfer coating components to a windshield significantly diminish in the time between wiper production and the actual installation of the blade on a vehicle. Additionally, the coatings imparted to a windshield tend to be irregular and create a mottled hydrophobicity.
Thus, there exists a need for a wiper blade coating that has a long-lasting shelf life after application to the wiper blade as to allow the coated wiper blade to impart a hydrophobic film to the contacted areas of the windshield rapidly during wiper blade operation and even after a long storage duration of wiper blade coating composition, and even at elevated temperature. There further exists a need for a process of applying an inventive coating composition to a wiper blade and the subsequent transfer of coating composition components to a contacted windshield.